Railway traffic controlling apparatus



I Approach 51010 Nov. 26, 1940. EH. THOMPSON 2,222,962

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed April 6, 1940 Apppoac'iz' JuuuuuuuuuuuL Ap pmozmedm F! czap IFHWHrwr-lmfimrwnmr 2. AbwaPdA. I 522 573 222.

H15 ATTORNEY Patented Nov. 26, 1940 UNITED STATES rarer orrlce RAILWAYTRAFFIC CONTROLLING APPARATUS Howard A. Thompson, Edgewood, Pa.,- assignor to The Union Switch & Signal Company, Swissvale, Pa..,' a corporation of Pennsylvania.

Application April 6, 1940, Serial No. 328,327.

13 Claims.

Railway signal systems using direct current coded at different codes each of which has a cyclic pattern consisting of one on and one off period have been proposed. Thecn and off periods of each code have distinctive pre-selected durations, the polarity of the direct current being, however, either of positive or of negative polarity as may be more convenient. A code following relay of the neutral type is'operated in step with the on and off periods of the code to control slow acting decoding devices. Such decoding devices areflp foportioned for different slowacting periods and are responsive in different combinations according to the duration of the periods of the different codes, and in turn selectively govern signaling circuits.

A feature of my invention is the provision of novel and improved means for a time code system wherein the different codes have a polarity characteristic. That is direct current at times of positive polarity and at other times of negative polarity is coded at different time codes for selectively governing signaling circuits through decoding means which is selectively responsive to the polarity of the current as well as to the duration ofthe code periods.

Another feature of my invention is the provision of novel and improved apparatus of the type here contemplated wherewith the .duration of the code periods for the different codes are widely different and of durations such that a direct current polarized relaymay be used as a code following relay to operate a neutral contact carrying armature instep with the code periods and to position a polar contact carrying armature at a normal or a reverse position according to the polarity of the coded current.

A further feature of my invention is the provision in systems using time codes of novel and improved decoding means of simple and inex- 435 pensive construction.

Still another feature of my invention is the provision of novel and improved apparatus for a signal system for four-block five-indication railways. I I he above features, as well as other advantages of my invention; are obtained by providing two coding elements operable at widely different rates. Thatais, one such element operates to code direct current at a relatively low rate to create a time code pattern having relatively long on and off period-s, and the other of such elements operates to code the current at a relatively high rate to create a time code pattern having relatively short on and off periods. A pole changer is associated with such coding elements to pole change the circuit under selected l control conditions with the result thatthe coded current is of positive or negative polarity according as said pole changer is set at one or the other of its two positions. Hence the coded current has a polarity characteristic as well as distinctive time code pattern. 4

The code following relay which receives such coded current is a polarized relay of the type whose polar armature remains in the position to which it was last moved when the relay is deenergizedf The neutral contact carrying armature of such relay is therefore operated in step with the on and off periods of the particular code ap'- former and a decoding relay proportioned for preselected characteristics. Direct current is alternately supplied to -difi"erent portions of a primary winding of the decoding transformer over front and back neutral contacts of the code following relay to build up magnetic flux in the core of the transformer during each on and off period and which fiux is opposite in direction for the on and oil code periods. The decoding transformer and the associated charging circuit are proportioned so that magnetic saturationof the core is effected during a short code period and hencethe flux density built up in the core is not materially greaterfor the long code period than that effected for the short code period. It

follows that the electromoti've force induced in the secondary winding of the decoding transformer due to the reversal of the magnetic flux caused by operation of the code following relay is substantially of the same value for both of these codes. The time interval between successive electromotive forces induced in the transformer secondary winding is in accordance with the duration of the on and off periods, being of a relatively short interval when the code following relay is operated bythe code of the short on and. off periods and being of a relatively long in- 'terval when the code following relay is operated by the code of the long on and off periods.

The decoding relay is connectedto the secondary winding of the decoding transformer for energization of that relay by the electromotive force induced inthe secondary winding. Pref: erably rectifying means is interposed in the con nection of the decoding relay to'the secondary winding and the relay is supplied with impulses of unidirectional current. The decoding relay winding and the transformer secondary winding are proportioned as to their impedances so that the electromotive forces induced in the secondary winding in the manner described above cause the energization of the decoding relay to build up to a value sufficient to pick up the relay when the rate of occurrence of the electromotive forces corresponds to that of the code having the short on and off periods but that when the rate of occurrence of the electromotive forces corresponds to the code having the long on and off periods the energization of the decoding relay created by one electromotive force dies away before the next electromotive force appears and the decoding relay is not effectively energized and remains released. In other words, the decoding relay, the decoding transformer and the circuit associated therewith are proportioned so that when the electromotive forces induced in the, transformer secondary winding are time spaced apart by a short interval corresponding to the code of the short on and off periods, the decoding relay is effectively energized and picked up, but that when the electromotive forces aretime spaced apart by intervals corresponding to the code of the long on and off periods, the decoding relay is not effectively energized and is released. The decoding relay; is provided with a slow release period sufiicient to bridge the short interval but not the long interval.

' To further detect the presence of coded current I preferably use two slow release relays which check the operation of the code following relay by one of such relays being controlled over a front neutral contact of the code following relay and by the other of such relays being controlled over a back neutral contact of the code following relay and a front contact of the first mentioned of such relays. 1

Contacts of the decoding relay and polar contacts of the code following relay are used to selectively govern signaling circuits, such circuits being also controlled preferably by the second mentioned check relay.

I shall describe one form of apparatus embodying my invention and shall then point out the novel features thereof in claims. y

In the accompanying drawing, Fig. 1 is a diagrammatic view showing one form of apparatus embodyingmy invention when used for a fourblock five-indication wayside signal system for railways. Fig. 2 is a diagram showing four different polar time codes that may be used with the apparatus of Fig. 1. It will be understood that I do not Wish to limit my invention to this one form of apparatus, and this one form will serve to illustrate the many places where apparatus embodying my invention is useful.

Referring to Fig. 1, the reference characters la and lb designate the track rails of a stretch of railway over which traffic normally moves in the direction indicated by an arrow, and which rails areformed by the usual insulated rail joints into consecutive track sections of which sections only one section WX and the adjoining ends of the two adjacent sections are shown for the sake of simplicity since these are sufficient for a full understanding of my invention. v

Each track section is provided with a track circuit comprising coded current supply means connected across the rails at one end of the section and a code following relay connected across an understanding of all. The immediate sourceof coded current for the track circuit of section WX is a battery KB and two relays XR and XP. When relay XP is picked up, closing front contacts 3 and 4, and relay XR is picked up closing front contact 5, the battery XB is connected across the rails adjacent the exit end of section WX and direct current is supplied to the track circuit, the current being of what I shall term positive polarity. 'When relay XP is released closing back contacts 6 and l and relay XR is picked up to close front contact 5, the battery XB is connected to the rails and direct current is supplied to the track circuit butthe current is of negative polarity since the connection is pole changedat back contacts 6 and l of relay XP. When relay XR is released to open front contact the battery XB is disconnected from the railsand no current is supplied to the track circuit. Thus with relay XR operated according to a predee termined cycle consisting of a period in which the relay is picked up and a corresponding period in which the relay is released, the current of the track circuit of section WX has a cycle pattern corresponding to the cycle at which relay XR. is operated. Such coded current is of positive polarity when relay XP is picked up and is of negative polarity when relay XP is released. It

follows that relay XP and KR are operable to code the track circuit current with'difierent codes each of which has a polarity characteristic as well as a distinct time code pattern.

Four different polar time codes that may be created by relays XR and IQ are illustrated by the diagrams in Fig. 2, inwhich a flow of current of negative polarity is represented by the portions of a diagram below the base line and a flow of current of positive polarity is represented by the portions of a diagram above the base line. Under a first or approach condition, relay XP is released and relay XR is operated at a rate of, say, 20 cycles per minute or once every three seconds, relay XR. being picked up for substantially one and one-half seconds and released for substantially one and one-half seconds each operation cycle. Thus as illustrated in Fig. 2, an approach code has a cyclic pattern'consisting of a relatively long on and off period of one and onehalf seconds each and a negative polarity characteristic. Under asecond orapproach-slow condition, relay XP is released as before and relay XR is operated at the rate of, say, 120 cycles per minute or two cycles per second, relay XR' being picked up for one-fourth second and released for one-fourth second each operation cycle. The approach-slow code hence has a cyclic pattern consisting of a relatively short-on and off period of one-fourth second each and a negative polarity characteristic. Under a third or approachmedium condition, relay XP is picked up and relay XR is operated at the rate of 20 cycles per minute. The approach-medium code consists, therefore, of a cyclic pattern having relatively long on and off periods and a positive polarity characteristic. Under a fourth or clear condition, relay XP is picked up and relay XR is operated at the rate of 120 cycles per minute, and the clear code has a cyclic pattern of relatively short on and off periods and a positive polarity characteristic. The manner of controlling relays 2G and KR to effect the different polar time codes of Fig. 2 will appear hereinafter.

At the left-hand end of Fig. 1 there are shown a battery WB and relays WP and WR which function to supply coded current to the track circuit of the section next in the rear of section W-X in the same manner the battery XB and relays XP and KR function to supply code-d current to the track circuit of section W-X.

It is to be observed in connection with the codes of Fig. 2 that the code rate of 20 cycles per minute is a relatively low rate creating a code having long on and off periods and the code rate of 120 cycles per minute is a relatively high rate creating a code having short on and off periods.

It is to be understood, of course, that my invention is not limited to these specific code rates but such rates are satisfactory and are used to illustrate the invention.

The code following relay for the track circuit of section WX is a relay CF whose winding 8 is connected across the rails adjacent the entrance end of the section over wires 9 and I0. Relay CF is a direct current polarized relay of the type whose polar armature remainsin the positionto which it was last moved when the relay is deenergized. When current is supplied to the track circuit during an on period of a code and winding 8 of relay CF is energized, the front neutral contacts ii, If and I3 are closed and when no current is supplied to the track circuit during an off period of a code and winding 8 is deenergized. the back neutral contacts !4, l5 and i6 are closed, these neutral contacts of relay CF being thus operated in step with the on and off periods of the code impressed upon the track circuit current. When the track circuit current is of positive polarity the normal polar contacts ll, [8, l9 and 28 are closed and when the current is of negative polarity the reverse polar contacts El, 22, 23 and 2c are closed. During each 01f code period and relay CF is deenergized, the polar contacts remain in the position to which they are moved due to the energization of relay CF during the on code period. That is to say, the polar contacts.

of relay CF closed at the start of a code remain r closed as long as that code persists.

A decoding transformer DT is supplied with current in step with the operation of relay CF from a convenient source of direct current such as a battery, not shown, but whose terminals are indicated at B and C. The two half portions of primary winding 25 of transformer DT are alternately connected with the B and C terminals of the current source over front contact ll and back contact M of relay CF. When relay CF is picked up closing front contact ll, current flows in the top portion of primary winding 25 and magnetic flux builds up in one direction in magnetic core 28 of transformer DT. When relay CF is released to open front contact H and close back contact id the current to the top portion of primary winding 25 is interrupted and current flows in the lower portion of winding 25 and. the magnetic flux of core 28 dies down, passes through zero and builds up in the other direction due to such change in the flow of current in primary winding 25. When relay CF is picked up to open back contact i i and close front contact H, a corresponding change takes place in the current supplied to primary winding 25 and a corresponding variation of the magnetic flux in core 26 is effected except the relative directions of the current and magnetic flux are opposite to those effected when the relay is released. Each such variation or reversal of the magnetic flux of core 26 creates an electromotive force in secondary winding?! of transformer DT. The value of such electromotive force is within limit proportional to the density of the magnetic flux, since the rate of change is substantially the same for both pickup andrelease operations of relay CF. The transformer DT and its charging circuit are proportioned to effect substantially magnetic saturation of core 26 during a one-fourthsecond period which is the duration of the short code period of the track circuit current. It follows that the electromotive force induced in secondary wind-' ing 2'! is substantially the same whether relay CF is operated in step with the short code period of one-fourth second duration or in step with the long code period of one and one-half seconds duration. lhe time interval between successive electromotive forces induced in secondary wind-1 ing 21 is substantially the code period duration at which relay CF is operated. In other words when relay CF is operated at the high code rate the interval between successive clectromotive forces induced in secondary winding 2'l'is substantially one-fourth second and when relay CF is operated at the low code rate the interval be-. tween successive electromotive forces is substantially one and one-half seconds.

A decoding relay D is connected with secondary winding 2? for energization of that relay by the electrornotive forces induced in winding 21. Preferably winding 28 of relay D is connected with the top and lower portions of secondary winding 21 over front contact l2 and back contact it of relay CF so-that the electromotive forces are rectified and unidirectional current impulses are supplied to winding 28. Relay D is adjusted for a predetermined pick-up energization, The winding 28 of relay D and the secondary winding 21 of transformer DT are proportioned so that when the electromo-tive forces induced in secondary winding 21 are spaced apart about one-fourth second the energization of relay D is gradually built up and after a few such electro-motive forces the pick-up energization of relay D is efiected and relay D is picked up. Relay D is preferably slightly slow to release so that it does not release when the successive electromotive forces are spaced apart one-fourth second. However, when the electromotive forces are spaced apart one-and one-half seconds the energization of relay D ef lays FSA and BSA are provided and controlled over neutral contacts of the code following relay CF. Relay FSA is governed over a simple circuit includingfront contact l3 of relay CF and relay BSA is governed over a circuit including back contact it of relay CF and front contact 29 of relay FSA as will be readily understood by an inspection of Fig. 1. Consequently these two relays FSA and BSA are energized and'retained picked up only when relay CF is operated to alternately close front contact l3 and back contact l6, relays FSA and BSA being provided with slow release periods sufiicient to bridge the long code period referred to hereinbefore. Y The decoding relay D and polar contacts of relay CF selectively control the operative cir- "*"cuits of a wayside signal WS which governs traflic through section WX, such signal operating circuits being also governed by check relay BSA. In a similar manner, decoding relay D, check relay BSA and polar contacts of relay CF are used to control the supply of coded current to the track circuit for the section next in the rear of section WX. That is to say that in order to reflect different traffic conditions in advance of such section next in the rear, the track circuit current for that section is controlled by relays D,

BSA and CF associated with section WX, such current being coded by one or the other of two coding devices ZUCT and IZOCT.

The coding devices or code transmitters 200T and vl2llCT may be any one of several types of coding devices and as shown are of the relay type provided with a code contact element or member which is operated in a cyclic manner as long as the operating winding of the code transmitter is and one-half seconds and is open for a period of one and one-half seconds each operation cycle of the code transmitter. The code transmitter |20CT is similar in construction except its contact member 32 is operated at the rate of 120 cycles per minute or 2 operation cycles per second, contact member 32 being raised to engage a contact 33 for one-half of each operation cycle and lowered to disengage contact 33 for one-half of each operation cycle. As will shortly appear, contact member 30 of code transmitter 20CT is used to create long code periods and contact member 32 of code transmitter |20CT is used to create short code periods.

The wayside signal FS may be any standard type of signal and as shown is a color light signal capable of displaying five different signal indications. It is believed that the operating cir cuits for signal WS, as well as the circuits for supplying coded current to the track circuit next in the rear of section WX can best be understood by a description of the operation of the apparatus.

It is to be observed that relay XR and relay XP are controlled by the apparatus associated with the section next in advance of section WX in the same manner that relays WR and FF for the section next in the rear of section W-X are controlled by the apparatus associated with the track circuit of the section WX.

I shall first assume that a train occupies section WX to shunt the track circuit so that code following relay CF is inactive with its back neutral contact closed. Under this condition decoding relay D is deenergized and released becauseino electromotive forces are induced in secondary winding 21 of transformer DT, and check relays FSA and BSA are deenergized and released because relay CF is inactive. With r'elay BSA released an operating circuit can be traced from terminal B of the current source over back contact 34 of relay BSA, lamp R of the top group of lamps of signal WS and terminalC, and lamp R is illuminated. Also an operating circuit extends-from terminal B over back contact 35 of relay BSA, lamp R of the lower group of lamps of signal WS and to terminal C, and this lamp R is also illuminated so that signal WS displays a red lamp above a ,redlamp for a stop signal indication.

Theicontrol circuit for relay WP is now open at both front contact 36 of relay D and front contact 31 of relay BSA, as will be apparent by an inspection of Fig. 1 and relay WP is released to close its back pole'changing contacts 42 and 43. Relay WR is provided with a circuit including terminal B, contact 30-3l of code transmitter 200T, back contact 38 of relay BSA, winding of relay WR and to terminal 0, and relay WR is operated in step with operation of contact member 30. Since relay WP is released and relay WR operated at the code rate of 20 cycles per minute the track circuit current of the section next in the rear of section WX is coded according to the approach code of Fig. 2 when the train occupies section WX. V

I shall next assume that the train moves to the right out of section WX and occupies the section next in advance. The relay XP is released and relay XR. is operated at the rate of 20 cycles per minute, it being recalled that relays XR and X? are controlled by the apparatus for the section next in advance in the same manner that relays WP and WR are controlled by the apparatus of section WX. With relay XP released and relay XR operated at the rate of 20 cycles per minute, the track circuit current of section WX is coded at the approach code and code following relay CF operates its neutral contact members at a corresponding rate and moves its polar contact members to the reverse or right-hand position as viewed in Fig. 1. Relays FSA and BSA are picked up in response to such code operation of relay CF but decoding relay 'D remains released because of the long interval between successive electromotive forces induced in secondary winding 21 of transformer DT. With relay BSA picked up and relay D released and the reverse polar contacts of relay CF closed, an operating circuit can be traced from terminal B over front contact 39 of relay BSA, reverse polar contact 24 of relay CF, lamp Y of the top group of lamps of signal WS and to terminal C, and this lamp Y is illuminated. Also an operating circuit extends from terminal B over front contact 40 of relay BSA, reverse polar contact 22 of relay CF, back contact 4| of relay D, lamp-R of the lower group of lamps of signal WS and to terminal C, and lamp R is illuminated so that signal WS displays a yellow light over a red light for an approach signal indication. The circuit for relay WP is open the same as before and this relay is released closing back contacts 42 and 43. Relay WR is controlled over a circuit involving terminal B, contact 3233 of code transmitter I20CT, back contact M of relay D, reverse polar contact 2| of relayCF, front contact 45 of relay BSA, winding of relay WR and terminalC, and relay WR' is operated at the rate of 120 cycles per minute so that the track circuit current for the section next in the rear is coded at the approachslow code of Fig. 2 when section WX is unoccupied and a train occupies the section next in advance of section WX.

Assuming next that the train advances one more section to the right to, occupy the second section in advance of section WX and the first section in advance is unoccupied, the relay XP is released and relay XR is operated at the rate picked up.

of 120cycles per minute so that. the track circuit-current of section WX is-of the approachslow code. Code following relay CF now operates its neutral contact membersat the rate of 120 cycles per minute and its polar contact members are-stillretained at the reverse position. Relays FSA and BSA are picked up by the code operation of relay CF and decoding relay D is picked up because the'electromotive forces induced in secondary winding 27 are spaced apart only onefourth second. Under this condition of the relays an operating circuit is provided for lamp Y of the topgroup of lamps of signal WSthe same as before and another operating circuit extends from terminal B over front contact 40 of relay BSA, reverse polar contactZZ ofrelay CF, front contact 45 of relay D, lamp Y of the lower group of lamps-and to terminal C, and this lamp is 11- luminated so that signal WS displays a yellow light over a yellow light for an approach-slowsignal indication. The circuit for relay WP is now closed at front contact 36'of relay D and relay WP is picked up to close its front pole changing contacts 4'! and 48. Relay WR is'controlled over a circuit that can be traced from terminal B, contact 3D-3l of code transmitter ZllCT, front contact 49 'of relay D, reverse polar contact 2| of relay CF,.front contact 45 of relay BSA, winding of relay WR. and to terminal C, and relay WRis operated. at the rate of 20 cycles per minute. Hence the track circuit current for the section next in the rear is coded at the approachmedium code of Fig. 2 when there are two unoccupied sections in advance and the third section in advance is occupied.

Assruning that the train moves another section to the right to occupy the third sectionin advance of section WX, leaving thetwo sections next in advance of section WX unoccupied, the relay XP is picked up and relay XR is operated at the rate of 20 cycles per minute, it being again recalled that relays XR and X? are controlled in the same manner as relays WR and.

WP. With relay )G picked up and relay XR operated at the rate of 20 cyclesper minute the track circuit current is of the approach-medium code and relay CF operates its neutral contact.

carrying armature at the corresponding rate and positions its polar contact carryingarmature at the normal or left-hand position as viewed'in Fig. 1. Relays FSA and BSA are picked up the same as. before, but decoding relay D isreleased because of the long time interval between the successive electromotive forces included in secondary winding 21 of transformer DT. Under this condition of the relays. an operating circuit for lamp Y of the top group of lamps is completedfrom terminal B over front contact. 39 of relay BSA, normal polar contact 20 of. relay CF, back.

contact 50 of relay D, lamp Y and to terminal 0. Also an operating circuit is formed for lamp G of the lower group of lamps, from terminal B,,over front contact 48 of relay BSA, normal polar contact Id of relay CF, lamp G. andto terminal-C. Thus signal WS displays a yellow light over a green light for an approach-medium signal indication. The circuit for relay WP isnow closed at normal polar contact IQ of relay CF and front contact 3'! of relay BSA so that relay WP -is formed from terminal. B, over contact 3.233 of code transmitter 1213GT, normal polar contact I! of relay CF, front contact 45 of'relay BSA, winding of relay WR and to terminal. 0, and relay WR is operated at the rate of 120v cycles per minute Relay WR iscontrolled by a circuit.

so that the track-circuit current of the associated section is coded at the clear code of Fig. 2 when there are three unoccupied sections next in ad-v andD to be all picked up. An operating circuit is now formed for the G lamp of the top group of lamps from terminal B over front contact 39 of relay BSA, normal polar contact 20 of relay CF, front contact 5| of relay D,lamp Gand to terminal C. A second operating circuit is formed from terminal B over front contact 40 of'relay BSA, normal polar, contact 18 of relay CE, lamp.

G of the lower group of lamps and to terminal 1 C, and signal WS displays a green light over a green light fora clear signal indication. Circuits for relays WP and WE are formed the same as before and the track circuit current or the p associated section is still coded at the clear code.

It is apparent that with thedecoding trans former DT proportioned for magnetic saturation at the short code periods the usual variations caused. by variations of voltagesof the current sourcecreates little if any variation. in the electromotive force induced in secondary. winding 21.

Furthermore, since the difference .between the,

While I.have disclosed my invention asused to provide four different codes for afour-block five-indication signal system,lit is contemplated that the invention may be used to provide three different codes for a three-block four-indication signalsystem, leaving the fourth code to beused for somespecial control such as the control of. a highway crossing signal, if desired. Again, two. codes may be usedto eifect a two-block three-indication signalsys'tem leaving two codes for special controls, if desired. Y

Although I have herein shown and described only one form of railway traffic controlling ap v paratus embodying my invention, it will be understood that various changes and modifications may be made therein within the scope of. the

ppended j claims without departing from thespirit and scope of my invention.

I-Iaving thus described my invention, what I claim. is: I

1. In railway trafiic controllingv apparatus for use with a track circuit supplied at times with current of positive polarity coded atv a preselected code rate and at other times with current of negative polarity coded at said prese-.

lected code-rate for operating the neutral con tact carrying, armature of a polarized code following relay connected with said circuit at said code rate and for positioning the polar contact carrying armatureat a normal ora reverse position according to the polarity of such coded cur rent, the combination comprising, a decoding relay, an impedance element, circuit means including said impedance element and a contact of said neutral armature to energize said decoding relay and said circuit means proportioned to effectively energize the decoding relay to pick up the relay only when said code following relay is operated at said preselected code rate, and si naling circuits selectively controlled over contacts of said decoding relay and normal and reverse contacts of said polar armature.

2. In railway traffic controlling apparatus for use with a track circuit supplied at times with current of positive polarity coded at a preselected code rate and at other times with current'of negative polarity coded at said preselected code rate for operating the neutral contact carrying armature of a polarized code following relay connected with said circuit at said code rate and for positioning the polar contact carrying armature at a normal or a reverse posi tion according to the polarity of such coded current, the combination comprising, a decoding transformer, a decoding relay, circuit means including a front and a back contact of said neutral armature to alternately supply direct current to two portions of a primary winding of said transformer to induce electromotive forces in a secondary winding of the transformer at a rate corresponding to said code rate, other circuit means including another front .and back contact of said neutral armature to connect said secondary winding to a winding of said decoding relay to energize the decoding relay by said electromotive forces, said secondary winding and' said decoding relay winding proportioned to build up the energization of the decoding relat sufficient to pickup that relay only when said electromotive forces are of a rate at least equal to that corresponding to said code rate, and signaling circuits selectively controlled over contacts of said decoding relay and normal and re-.

verse contacts of said polar armature.

, 3. In railway trafiic controlling apparatus for use with a track circuit supplied with coded current at times of positive polarity and at other times of negative polarity and which code has a cyclic pattern of one on and one off period of equal preselected durations and to which circuit is connected a polarized .code following relay for operating a neutral contact member in step with the code periods and for positioning a polar contact member at a normal or a reverse position according-to the polarity of the coded current, the combination comprising, a decoding transformer, circuit means including said neutral contact member to supply direct current to a primary winding of said transformer to induce in a secondary winding of the transformer electromotive forces spaced apart by intervals substantially equal to the duration of said code periods, a decoding relay having a winding connected to said secondary winding'for energization of the relay by said electromotive forces and said decoding relay proportioned so that the energization builds up sufficiently to pick up the decoding relay only when the electromotive forces are spaced apart by intervals not greater than said code period duration, a first signaling circuit including a front contact of said decoding relay and said polar contact member at its'normal position, and a second signaling circuit including a front contact of said decoding relay and said polar contact member at its reverse position.

4. In railway traffic controlling apparatus for use with a track circuit supplied with coded current at times of positive polarityand at other times of negative polarity and which code has a cyclic pattern of one on and one off period of equal preselected durations and to which circuit is connected a polarized code following relay for operating a neutral contact carrying armature in step with the code periods and for positioning a polar contact carrying armature according to the polarity of the coded current, the combination comprising, a decoding transformer, circuit means including a front and a back contact of said neutral armature to alternately supply direct current to two portions of a primary winding of said transformer to induce in a secondary winding of the transformer an electromotive force at intervals substantially equal to said code period duration, a decoding relay, other circuit means including a front and a back contact of said neutral armature to connect said secondary winding to a winding of said decoding relay for energization of that relay by unidirectional current impulses spaced apart by intervals corresponding to said code period duration, said decoding relay characterized by its energization building up sufiiciently to pick up the relay only when said current impulses occur at intervals not greater than said code period duration, a first signaling circuit including a front contact of said decoding relay and a normal contact of said polar armature, and a second signaling circuit including a front contact of said decoding relay and a reverse contact of said polar armature.

5. In railway traffic controlling apparatus for use with a track circuit supplied at times with coded current of a predetermined low code rate and at other times with coded current of a predetermined high code rate for operating a code following track relay at a rate corresponding .to the code rate of the track circuit current, the combination comprising, a decoding transformer having apreselected magnetic core, a charging circuit including a front contact of said code following relay to connect a source of direct current to a primary winding of said transformer to periodically create a magnetic flux insaidcore and induce in a secondary winding of the transformer electromotive forces .having a rate of occurrence corresponding to the code rate at which said code following relay is operated, said charging circuit proportioned to effect magnetic saturation of said magnetic core during a code period of said high code rate and electromotive forces of substantially the same value are induced in the secondary winding for both code rates, a decoding relay, rectifying means to connect said secondary winding to a winding of said decoding relay to energize the decoding relay by unidirectional current impulses created by said electromotive forces, said decoding relay characterized by the building up of its energization sufiicient to pick up the relay when such current impulses occur at a rate corresponding to said high code rate but not to said low code rate, and a signaling device distinctive to said high code rate controlled over a front contact of said decoding relay.

6. In railway traflic controlling apparatus for use with a track circuit supplied at times with coded current of a predetermined low code rate and at other times with coded current of a predetermined high code rate for operating a code following track relay at a rate corresponding to the code rate of the track circuit current, the

combination comprising, a decoding transformer having a preselected magnetic core, a charging circuit including a front contact of said code following relay to connect a source of direct current to a primary winding of said transformer to periodically create a magnetic flux in said core and induce in a secondary winding of the transformer electromotive forces having a rate of occurrence corresponding to the code rate at which said code following relay is operated, said charging circuit proportioned to effect magnetic saturation of said magnetic core during a code period of said high code rate and electromotive forces of substantially the same value are induced in the secondary winding for both code rates, a decoding relay, circuit means including a contact ofsaid code following relay to connect said secondary winding to a winding of said decoding relay to supply an energizing current impulse to said decoding relay in response to each of said electrometive forces, said secondary winding and decoding relay winding proportioned as to their impedances so that the energization of the decoding relay builds up suficiently to pick up that relay when "the electromotive forces are of the rate corresponding to said high code rate but not to said low code rate, and a signaling device distinctive to said high code rate controlled over a front contact of said decoding relay.

7. In railway trafilc controlling apparatus for use with a track circuit supplied at times with coded current of a predetermined low code rate and at other times with coded current of a predetermined high code rate for operating a code following track relay at a rate corresponding to the code rate of the track circuit current, the combination comprising, a decoding transformer having a preselected magnetic core, a charging circuit including a front contact of said code fol- 0 lowing relay to connect a source of direct current to a primary winding of said transformer to periodically create a magnetic flux in said core and induce in a secondary winding of the transformer electromotive forces having a rate of 5 occurrence corresponding to the code rate at which said code following relay is operated, said charging circuit proportioned to effect magnetic saturation of said magnetic core during'a code period of said high code rate and electromotive 0 forces of substantially the same value are induced in the secondary winding for both code rates, a decoding relay, circuit means including a contact of said code following relay to connect said secondary winding to a winding of said decoding relay to supply an energizing current im.- pulse to said decoding relay in response to each of said electromotive forces, said secondary winding and decoding relay winding proportioned as to their impedances so that the energization of 0 the decoding relay builds uplsufficiently to pick up that relay when the electromotive forces are of the rate corresponding to said high code rate but notto said low code rate, another relay, circuit means including a frontland a back contact 5 of said code following relay to effectively energize said other relay when the code following relay is operated, and signaling circuits selectively controlled by said decoding relay and said other relay. 7 0 8. In railway traffic controlling apparatus for use with a track circuit supplied at times with current of positive polarity coded at either a predetermined high or low code rate and at other times with current of negative polarity coded at 5 either said high or said low code rate, the combination comprising, .a polarizedcodef'ollowing relayconnected to said track circuit for operation of a neutral contact carrying armature at a rate corresponding to the code rate of the track circuit current andnto position a polar contact, carryingrarmatureat a normal or'a reverse position according to the positive or'negative' polarity of said current, a decoding transformer having a magnetic core, a charging circuit including a contact of said neutral armature to supply direct current to a primary winding of said transformer to induce electromotive forces in a secondary winding of "thetransformer at a rate correspondingto' the rate at which said code, following relay-iscperated, said charging circuit and trans-. fcrmer pr'oportioned to effect magnetic 'satura tion of said magnetic core during the code period of :said high code rate to induce electromotive forces of substantially equal value for both said code :rates, a decoding relay having a winding connected tosaid secondary winding, said relay winding and said secondarywinding proportioned to build up anenergi'zation sufIicient-to pick up said decoding relay in response to electromotive forces of the rate corresponding to said high code rate but not to said low code rate, and signaling circuits-selectively controlled over. contacts of saiddecoding relay and normal and reverse con-' tactsof said nolar'armature. I I 3 9; r Inrailway trafiic controlling apparatus for use with a track circuit supplied at times with current of positive polarity coded at either a predetermined high or low code rate and at other times with current of negative polarity coded at either said high or said low code rate, the combination comprising, a polarized code following relay connected to said track circuit foroperation of a neutral contact carrying armature at a rate corresponding to the code rateofithe track circuit current and to position apolar contact carrying armature at a normal or a reverse position according to the positive or negative polarity of said current, a decoding transformer having a magnetic .core, a charging circuit including a contact of said neutral armature to supply direct current to a primary winding of said transformer to induce electromotive forces in a secondary winding of the transformer at a rate corresponding to the rate at which said code following relay is operated, said charging circuit and transformer proportioned to effect magnetic saturation of said magnetic core during the code period of said high code rate to induce electro motive forces of substantially equal value for both said code rates, a decoding relay, circuit means including a front and a back contact of said neutral armature to connect said secondary winding to a winding of said decoding relay to supply unidirectional current impulses to the decoding relay at a rate corresponding to the rate of the electromotive force, said decoding relay characterized by the building up of its energization sufiicient to pick up that relay when such current impulses have a rate corresponding to said high code rate but notto said low code rate, and signaling circuits selectively controlled over contacts of said decoding relay and normal and reverse contacts of said polar armature.

10. In railway traffic controlling apparatus for use with atrack circuit, supplied at times with current of positive polarity coded-at either a predetermined high or low code rateand at other times with current of negative polarity coded at either said high or said low code rate, the combination comprising, a polarized code following relay connected-to said track circuit for operation of a neutral contact carrying armature at a rate corresponding to the code rate of the track circuit current and to position a polar contact carrying armature at a normal or a reverse position according to the positive or negative polarity of said current, a decoding transformer having a magnetic core, a charging circuit including a contact of said neutral armature to supply direct current to a primary winding of said transformer to induce electromotive forces in a secondary winding of the transformer at a rate corresponding to the rate at which said code following relay is operated, said charging circuit and transformer proportioned to effect magnetic saturation of said magnetic core during-the code period of said high code rate to induce electromotive forces of substantially equal value for both said code rates, a decoding relay having a winding connected with said secondary winding,

, said relay winding and said secondary winding proportioned to building up energization sufiicient to pick up said decoding relay in response to electromotive forces of the rate corresponding to said high code rate but not to said low code rate, another relay, circuit means including a front and aback contact of said neutral armature operative to energize said other relay when the code following relay is operated at either said high or low code rate, and signaling circuits selectively controlled over contacts of said decoding relay and said other relay as well as normal and reverse contacts of said polar armature.

11. In combination, a stretch of railway track divided into a plurality of consecutive track sections each provided with a track circuit, transmitting means for a given section for supplying to the track circuit of said given section direct current of negative polarity coded at a predetermined low rate, or of negative polarity coded at a predetermined high rate, or direct current of positive polarity coded at said low rate or of positive polarity coded at said high rate according to a first, a second, a third or a fourth traflic condition in advance of said given section, a polarized code following relay connected to said track circuit to operate a neutral contact carrying armature at the code rate of the track circuit current and to position a polar contact carrying armature according to the polarity of the current, a decoding transformer, a decoding relay, circuit means including contacts of said neutral armature and said transformer to energize said decoding relay and operative to pick up the decoding relay in response to track circuit current codedat said highrate but not said low rate, another relay, circuit means including contacts of said neutral armature effective toenergize said other relay in response to track circuit current of either of said code rates, a signal having a distinctive indication for each of said four mentioned traflic conditions, and an operating circuit for each of said signal. indications selectively controlled over contacts of said decoding relay, said other relay and contacts of said polar armature.

12. In combinatioma section of railway track, traflic governed means operative for supplying to the rails of said section direct current of negative polarity coded ata preselected low code rate or at a preselected high code rate or direct cur-.

rent of positive polarity coded at saidlow code rate or at said high code rate according, to four different traffic conditions in advance of said section, a polarized code following track relay connected to the rails of said section for operating its neutral armature at the code rate of such current supplied to the rails and for positioning its polar armature according to the polarity of such current, a decoding transformer having a magnetic core, a charging circuit including a front and a back contact of said track relay to supply direct current to a primary winding of said transformer and proportioned to create magnetic saturation of said core at said high code rate to induce in a secondary winding of said transformer electromotive forces of a rate corresponding to the code rate at which said track relay is operated but of substantially uniform value, a decoding relay connected to said secondary Winding over a front and a back contact of said track relay to energize the decoding relay by unidirectional current impulses created by said electromotive forces and said. decoding relay characterized by the building up of its energization sufficient to pick up that relay only when said track relay is operated at said high code rate, a signal for said section capable of displaying a distinctive indication for each of said four traflic conditions, and four operating circuits one for each of said signal indications selectively controlled by said decoding relay and polar contacts of said track relay.

13. In combination, a section of railway track, traffic governed means operative for supplying to the rails of said section direct current of negative polarity coded at a preselected low code rate or at a preselected high code rate or direct current of positive polarity coded at said low code rate or at said high code rate according to four different trafiic conditions in advance of said section, a polarized code following track relay connected tothe rails of said section for operating its neutral armature at the code rate of such current supplied to the rails and for positioning its polar armature according to the polarity of such current, a decoding transformer having a magnetic core, a charging circuit including a front and a back contact of said track relay to supply directcurrent to a primary winding of said transformer and proportioned to create magnetic saturation of said core at said high code rate to induce in a secondary winding of said transformer electromotive forces of a rate corresponding to the code rate at which said track relay is operated but of substantially uniform value, a decoding relay connected to said secondary winding over a front and a back contact of said track relay to energize the decoding relay by unidirectional current impulses created by said electromotive forces and said decoding relay characterized by the building up of its energization sufficient to pick up that relay only when said track relay is operated at said high code rate, another relay, circuit means including a front and a back contact of said track relay effective to pick up said other relay when said track relay is operated at either said low or high code rate, a signal for said section capable of displaying a distinctive proceed indication of each of said four trafiic conditions and a fifth stop indication, and five operating circuits one for each of said five signal indications selectively controlled over contacts of said decoding relay and said other relay and polar contacts of said track relay.

HOWARD A. THOMPSON. 

